Chromophore Components Research Articles

Designing easily synthesizable non-fused small acceptors for organic solar cells

A new strategy of implementing intramolecular noncovalent interactions (INCIs) has been adopted to design readily synthesizable acceptors for enhancing power conversion efficiency (PCE) and interfacial modifications of organic solar cells (OSCs). Computational approaches like density functional theory (DFT) have contributed to enterprise and analyze in what manner distinct chromophore components interact to produce optical transitions as well as orbital energy levels. This research focuses on a thorough and general overview of five designed conjugated molecular systems (BTZM1-BTZM5) possessing non-covalent conformational locking as well as evaluations using DFT. After incorporating INCIs (SO, SN, and S-F) into structured backbones, the resultant acceptor materials (BTZM1-BTZM5) showed tunable energy levels, reduced band gaps, enhanced absorption maximum, minimum binding energy, improved dipole moments and charge mobilities. Upon coupling BTZM5 acceptor with P3HT donor the blended film created a uniform surface and tighter π-π stacking ensuing VOC of 2.20 eV. Various computational analysis of molecules has been conducted to further confirm the nature of interactions such as TDM, DOS, FMOs, and RDG. Thus, the occurrence of many INCIs to closely lock the conformation of organic π-conjugated molecules is essential to improve the effectiveness of OSCs.

S-Tetrazine-Bridged Photochromic Aromatic Framework Material.

Integrating fluorescent chromophores in aromatic frameworks could not only prevent aggregation-induced quenching caused by the π–π stacking interaction between the chromophore components but also confer new fluorescence properties. Herein, we report the fabrication of s-tetrazine-bridged aromatic frameworks TzAF by the incorporation of the smallest aromatic fluorophore, s-tetrazine (Tz), into the skeleton of a tetrahedrally connected lattice of aromatic frameworks. The thin films of TzAF coated on silica gel plates were found to exhibit reversible photoswitching fluorescence characteristics under alternate UV and visible-light irradiations with excellent fluorescence stability and high on/off contrast. The repeatable “on/off”fluorescence photoswitchability of the TzAF thin films was mechanistically attributed to light-induced reversible transformation between TzAF’s neutral and radical states.

Use of an ultraviolet light-activated persulfate process to degrade humic substances: effects of wavelength and persulfate dose.

Natural organic matter (NOM), commonly found in surface and ground waters, form disinfection by-products in drinking water. Generally, advanced oxidation processes (AOPs) featuring hydrogen peroxide are used to treat water; however, sulfate radical recently has been used to treat recalcitrant organics, because it is associated with a higher oxidation potential and more effective removal than hydroxyl radicals. Hence, in this research, we evaluated persulfate oxidation efficiency in terms of reductions in humic substance levels and investigated the degradation mechanism. The results showed that ultraviolet-activated persulfate effectively treated humic substances compared with hydrogen peroxide and direct irradiation. Treatment was dose and wavelength dependent; higher persulfate concentrations or shorter UV wavelengths were more effective for treating humic substances as high concentration sulfate radicals were created. The degradation mechanism was similar to that of hydrogen peroxide. Aromatic and chromophore components were more susceptible to degradation than were lower molecular weight components, being initially decomposed into the latter, reducing UV254 absorbance and the SUVA254. Lower molecular weight materials were eventually degraded to end products: NPOC levels fell. And we also treated the inflow of a drinking water treatment plant with persulfate, and humic substances were effectively removed.

Molecular Chromophore-DNA Architectures With Fullerenes: Optical Properties and Solar Cells.

Supramolecular chemistry allows the construction of complex molecular architectures and the design of collective photophysical properties. DNA is an attractive template to build such supramolecular architectures due to its helical structure, the defined distances between the bases and the canonical base pairing that results in precise control of the chromophore position. The tailored properties of DNA-templated supramolecules eventually allow their implementation into optoelectronic applications. For the generation of free charge carriers from photo-generated excitons, fullerenes can be utilized. We synthesized two fullerene derivates, one of which binds by electrostatic interactions to single-stranded DNA, while the other contains two 2′-deoxyuridine moieties and assembles specifically along oligo-2′-deoxyadenosines (dA20) as DNA template. The DNA-directed assembly of both fullerenes in aqueous solution was investigated by UV/Vis absorbance and circular dichroism (CD) spectroscopy. The specific interactions with DNA make fullerenes with the 2′-deoxyuridine moieties a significantly better component for supramolecular DNA architectures. We studied the fluorescence quenching of both fullerenes with a DNA chromophore assembly. To investigate one of the key properties for optoelectronic applications, that is the supramolecular structure of the DNA-based assemblies in the solid phase, we characterized the CD of supramolecular chromophore-DNA architectures in thin films. Remarkably, the helical chirality of the chromophore assemblies that is induced by the DNA template is conserved even in the solid state. Upon implementation into organic solar cells, the external quantum efficiency measurements showed charge carrier generation on all three chromophore components of the DNA assemblies. The fullerenes with the 2′-deoxyuridine moieties enhance the quantum efficiency of the conversion process significantly, demonstrating the potential of DNA as structural element for ordering chromophores into functional π-systems, which may be employed in future organic solar cells.

Extracellular Oxidases of Basidiomycete Neonothopanus nambi: Isolation and Some Properties.

Using the original technique of treating biomass with β-glucosidase, a pool of extracellular fungal enzymes was obtained for the first time from the mycelium of basidiomycete Neonothopanus nambi. Two protein fractions containing enzymes with oxidase activity were isolated from the extract by gel-filtration chromatography and conventionally called F1 and F2. Enzyme F1 has a native molecular weight of 80-85 kDa and does not contain chromophore components; however, it catalyzes the oxidation of veratryl alcohol with Km = 0.52 mM. Probably, this enzyme is an alcohol oxidase. Enzyme F2 with a native molecular weight of approximately 60 kDa is a FAD-containing protein. It catalyzes the cooxidation of phenol with 4-aminoantipyrine without the addition of exogenous hydrogen peroxide, which distinguishes it from the known peroxidases. It was assumed that this enzyme may be a mixed-function oxidase. F2 oxidase has Km value 0.27 mM for phenol. The temperature optimums for oxidases F1 and F2 are 22-35 and 55-70°C, and pH optimums are 6 and 5, respectively.

Characterization of Chromophoric Water-Soluble Organic Matter in Urban, Forest, and Marine Aerosols by HR-ToF-AMS Analysis and Excitation-Emission Matrix Spectroscopy.

Chromophoric water-soluble organic matter in atmospheric aerosols potentially plays an important role in aqueous reactions and light absorption by organics. The fluorescence and chemical-structural characteristics of the chromophoric water-soluble organic matter in submicron aerosols collected in urban, forest, and marine environments (Nagoya, Kii Peninsula, and the tropical Eastern Pacific) were investigated using excitation-emission matrices (EEMs) and a high-resolution aerosol mass spectrometer. A total of three types of water-soluble chromophores, two with fluorescence characteristics similar to those of humiclike substances (HULIS-1 and HULIS-2) and one with fluorescence characteristics similar to those of protein compounds (PLOM), were identified in atmospheric aerosols by parallel factor analysis (PARAFAC) for EEMs. We found that the chromophore components of HULIS-1 and -2 were associated with highly and less-oxygenated structures, respectively, which may provide a clue to understanding the chemical formation or loss of organic chromophores in atmospheric aerosols. Whereas HULIS-1 was ubiquitous in water-soluble chromophores over different environments, HULIS-2 was abundant only in terrestrial aerosols, and PLOM was abundant in marine aerosols. These findings are useful for further studies regarding the classification and source identification of chromophores in atmospheric aerosols.

Dynamics of Protein Elements of Hybrid Nanostructures - Molecular Dynamics Simulations of Light Harvesting Peridinin-Chlorophyll a-Protein Model

Hybrid nanostructures are often composed of inorganic parts and biological ones. Optimized through million years of evolution light harvesting proteins are hard to mimic synthetically. Promising strategy in search for e cient solar cells is an attachment of selected natural protein systems to inorganic quantum dots. Such experimental hybrid structures should have improved charge separation properties. Among the most promising proteins is peridinin chlorophyll protein from Amphidinium carterae (PCP). It has a wide absorption spectrum (420 550 nm), optimized for sunlight. The dynamics of this protein, used in modern nanotechnology has been not addressed yet. In this work we present results of PCP computer modeling using a well established molecular dynamics methodology. The CHARMM27 force eld parameters were prepared for this protein and all chromophore components. The system was embedded in a box of water, with proper counter ions, and a number of 10 ns molecular dynamics simulations were run using the NAMD code. It has been found that peridinine chromophores exhibit substantial orientational exibility but a pair Per612 and Per613 is more rigid than the remaining two carotenoids. Orientation and dynamics of absorption and emission electric dipole moments have been also analyzed. Apparently, the architecture of PCP is not optimized for e cient Per Chl a energy transfer by the Forster mechanism. Several practical issues related to molecular dynamics simulation of similar hybrid nanostructures are discussed.

Optimal Efficiency of Self-Assembling Light-Harvesting Arrays

Using a classical master equation that describes energy transfer over a given lattice, we explore how energy transfer efficiency along with the photon capturing ability depends on network connectivity, on transfer rates, and on volume fractions-the numbers and relative ratio of fluorescence chromophore components, e.g., donor (D), acceptor (A), and bridge (B) chromophores. For a one-dimensional AD array, the exact analytical expression (derived in Appendix A) for efficiency shows a steep increase with a D-to-A transfer rate when a spontaneous decay is sufficiently slow. This result implies that the introduction of B chromophores can be a useful method for improving efficiency for a two-component AD system with inefficient D-to-A transfer and slow spontaneous decay. Analysis of this one-dimensional system can be extended to higher-dimensional systems with chromophores arranged in structures such as a helical or stacked-disk rod, which models the self-assembling monomers of the tobacco mosaic virus coat protein. For the stacked-disk rod, we observe the following: (1) With spacings between sites fixed, a staggered conformation is more efficient than an eclipsed conformation. (2) For a given ratio of A and D chromophores, the uniform distribution of acceptors that minimizes the mean first passage time to acceptors is a key point to designing the optimal network for a donor-acceptor system with a relatively small D-to-A transfer rate. (3) For a three-component ABD system with a large B-to-A transfer rate, a key design strategy is to increase the number of the pathways in accordance with the directional energy flow from D to B to A chromophores. These conclusions are consistent with the experimental findings reported by Francis, Fleming, and their co-workers and suggest that synthetic architectures of self-assembling supermolecules and the distributions of AD or ABD chromophore components can be optimized for efficient light-harvesting energy transfer.

ChemInform Abstract: The Synthesis of Highly Active Thiophene Ring-Containing Chromophore Components for Photonic Polymers Based on a Newly Designed Route.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

A single chromoprotein with triple chromophores acts as both a phytochrome and a phototropin.

Plants sense their environmental light conditions by using three photoreceptors that absorb in the UV, blue/near UV, and red/far-red spectral ranges. These photoreceptors have specific chromophore components corresponding to their absorption spectra. Phytochrome, a red/far-red light receptor, has phytochromobilin as its chromophore, whereas the blue/near UV photoreceptors cryptochrome and phototropin have a pair of flavin derivatives. Plants use these various photoreceptors to assess the surrounding light environment. Phytochrome 3 (PHY3) is a red light receptor found in some ferns, which preferentially grow under weak light. PHY3 is composed of a phytochrome chromophore-binding domain in its N-terminal portion and an almost full-length phototropin in its C-terminal half. This unusual domain organization implies that two different light-sensing systems coexist in this single photoreceptor, although these light-sensing systems usually reside in independent photoreceptors. Here, we show that PHY3 acts as a dual-channel photoreceptor that possesses both the red light-sensing system of phytochrome and the blue light-sensing system of phototropin. Furthermore, red- and blue-light signals perceived by PHY3 are processed synergistically within this single chromoprotein. These unusual properties might confer an enhanced light sensitivity on PHY3, allowing ferns to grow under a low-light canopy.

Effect of Conjugation Length on Intrachain Chromophore−Chromophore Interaction in Silylene-Spaced Divinyloligoarene Copolymers

A range of silylene-spaced divinyloligoarene alternating copolymer 3 has been synthesized regioregularly by rhodium-catalyzed hydrosilylation of bis(alkynes) 5 with bis(silanes) 6. Monomeric reference compounds 4 having similar chromophore components were also prepared for comparison. The silylene moieties serve as insulating spacers between chromophores. Intrachain interaction appears to be negligible due to the localization of exciton in these conjugated chromophores, resulting in the emission that closely resembles that of the parent chromophore.

Synthesis, light-harvesting and energy-transfer properties of regioregular silylene-spaced alternating [(donor-SiMe2-)(n=1-3)-(acceptor-SiMe2)] copolymers.

A series of silylene-spaced alternating [(donor-SiMe2)(n=1-3)-(acceptor-SiMe2)] copolymers 4-6 was synthesized by rhodium-catalyzed hydrosilylation of bisalkynes with bissilyl hydrides. Monomeric reference compounds 7-10 with similar chromophore components were prepared for comparison. The ratio of donor to acceptor groups is well-controlled by the precise regiochemistry and nature of the repeat units. The silylene moieties serve as insulating spacers between chromophores. The polymers exhibit light-harvesting abilities, for which the intensity of the emission enhanced with larger donor-to-acceptor ratios. No emission originating from the donors was observed in fluorescence spectra, illustrating that intrachain energy transfer is highly efficient along the polymer chain.

Determination of Imidacloprid in Fruits and Vegetables by Liquid Chromatography with Diode Array and Nitrogen-Specific Chemiluminescence Detection

A national trend is focusing on expanding usage of environmentally friendly nitrogenous pesticides and herbicides. However, some of these chemicals are undetectable by any gas chromatographic method due to their thermal lability or nonvolatility. Using imidacloprid as a model compound, this laboratory has developed a simple, effective, and reliable liquid chromatography (LC) method to address the inherent difficulties of these chemicals. Focusing on nitro, nitrate, and/or nitrite chromophore groups and components contained in the chemical structure of most nitrogenous compounds, LC with diode array detector and a nitrogen-specific detector in tandem enabled determination and confirmation analyses in series. Furthermore, using 2 mixtures of solvents in conjunction with 2-stage solid-phase extraction cleanup on aminopropyl/Florisil cartridges to eliminate and/or minimize interferences resulting from free amino acids, peptides, proteins, pigments, and lipids in the plant tissues made the qualitative and quantitative analysis simple, fast, and cost effective. This method demonstrated the potential for becoming a viable analysis tool for many other types of nonvolatile nitrogenous chemicals.

The synthesis of highly active thiophene ring-containing chromophore components for photonic polymers based on a newly designed route

2-Aminothiophene derivatives are the key intermediates for the present synthesis. It is known that the synthesis of 2-aminothiophene is troublesome although it is a rather simple heterocycle. In this work, an early report was newly developed as a basis for the efficient synthesis of thiophene-ring-containing chromophore components for photonic polymers. 2-Amino-5-nitrothiophene and 2-amino-3,5-dinitrothiophene were synthesized in excellent yield. After diazotization, the 2-aminothiophene derivatives were directly treated with N-phenyldiethanolamine to afford two-electron push–pull compounds. A similar styryl compound was also prepared. All of these chromophore molecules have further polymerizable hydroxy groups on one end of the molecule. These compounds are currently showing interesting potential in making highly sensitive, nonlinear optical polymeric materials.

Active site mutants implicate key residues for control of color and light cycle kinetics of photoactive yellow protein.

To understand how the protein and chromophore components of a light-sensing protein interact to create a light cycle, we performed time-resolved spectroscopy on site-directed mutants of photoactive yellow protein (PYP). Recently determined crystallographic structures of PYP in the ground and colorless I2 states allowed us to design mutants and to study their photosensing properties at the atomic level. We developed a system for rapid mutagenesis and heterologous bacterial expression for PYP apoprotein and generated holoprotein through formation of a covalent thioester linkage with the p-hydroxycinnamic acid chromophore as found in the native protein. Glu46, replaced by Gln, is buried in the active site and hydrogen bonds to the chromophore's phenolate oxygen in the ground state. The Glu46Gln mutation shifted the ground state absorption maximum from 446 to 462 nm, indicating that the color of PYP can be fine-tuned by the alteration of hydrogen bonds. Arg52, which separates the active site from solvent in the ground state, was substituted by Ala. The smaller red shift (to 452 nm) of the Arg52Ala mutant suggests that electrostatic interactions with Arg52 are not important for charge stabilization on the chromophore. Both mutations cause interesting changes in light cycle kinetics. The most dramatic effect is a 700-fold increase in the rate of recovery to the ground state of Glu46Gln PYP in response to a change in pH from pH 5 to 10 (pKa = 8). Prompted by this large effect, we conducted a careful reexamination of pH effects on the wild-type PYP light cycle. The rate of color loss decreased about 3-fold with increasing pH from pH 5 to 10. The rate of recovery to the colored ground state showed a bell-shaped pH dependence, controlled by two pKa values (6.4 and 9.4). The maximum recovery rate at pH 7.9 is about 16 times faster than at pH 5. The effect of pH on Arg52Ala is like that on wild type except for faster loss of color and slower recovery. These kinetic effects of the mutations and the changes with pH demonstrate that both phases in PYP's light cycle are actively controlled by the protein component.

Surface-Enhanced Resonance Raman Scattering of R-Phycoerythrin Adsorbed by Silver Hydrosols

Surface-enhanced resonance Raman scattering (SERRS) of R-phycoerythrin adsorbed by silver hydrosols was obtained. There are thirty-five lines in its SERRS spectra. However, there is a “fluorescent packet” in its Raman spectra only. All lines are covered up by the “packet”. The SERRS spectra were enhanced and the fluorescence was quenched rapidly because of the formation of the hydrosol/phycoerythrobilin (PEB) complex and the interaction with the SERS-active surface of the metallic base. The R-phycoerythrin consists of PEB and its surrounding protein matrix, but the lines of PEB appeared in R-phycoerythrin SERRS spectra only. This result indicates again that a competitive binding exists in the binding of protein-bound chromophore (R-phycoerythrin) components with silver hydrosols; thus, the chromophores (PEB) are mainly responsible for the SERRS effect. Therefore, the SERRS technique is very useful for studying protein-bound chromophores.

Largomycin FII chromophore component 4, a new pluramycin antibiotic.

The chromophore of the antitumor chromoprotein largomycin FII is a mixture of components belonging to the pluramycin class of antitumor antibiotics. Against most organisms tested, component 4 exhibited activity equal to or greater than the major chromophore components pluramycin A and deacetylpluramycin A. Data obtained from UV, IR, 1H and 13C NMR, and from fast atom bombardment mass spectrometry were used to determine the structure of component 4 as epoxykidamycin, a new member of the pluramycin class.

Structure and properties of major largomycin FII chromophore components.

Largomycin FII, a protein antitumor antibiotic of molecular weight 29,300 daltons, contains a chromophore that is separable under mild denaturing conditions. The chromophore complex was found to be considerably less stable than the holoprotein towards light and heat, suggesting a protective effect of the protein on the chromophore. Separation of the chromophore into several components was achieved using high performance liquid chromatography, and the biological activity of the isolated components was determined. Data gathered from UV, IR, proton and carbon NMR, and fast atom bombardment mass spectrometry indicated that all the chromophore components belong to the pluramycin class of antitumor agents. Pluramycin A and deacetylpluramycin A were found to be the two major components.

Purification and characterization of macromomycin-I, a protein antibiotic containing a non-protein chromophore

One-step chromatography of crude macromomycin on DEAE-Sephacel yielded two forms of the antibiotic. The more active form of the drug contained a non-protein chromophore. Apoprotein and chromophore components of this drug form were separated. The apoprotein was found to be inactive and the chromophore only slightly active against Sarcina lutea , while recombination of both components resulted in a partial recovery of the activity. In contrast, recombination of chromophore and apoprotein did not restore the ability of intact macromomycin to nick isolated DNA.

Fluorescent chromophore components from the egg capsules of the gastropod mollusc Buccinum undatum (L.), and their relation to fluorescent compounds in other structural proteins

1.1. The egg capsules from the gastropod mollusc Buccinum undatum contain a yellow fluorophore with aldehydic functional groups.2.2. The fluorophore-chromophore was partially purified by gel-filtration and ion-exchange chromatography.3.3. Partial hydrolysis and electron microscopic examination suggest that the egg capsules contain a resistant cross-linked core.4.4. There is evidence for the association of the fluorophore with the cross-linked core of the protein.5.5. Comparison is made between the fluorophore and fluorescent moieties found in other structural proteins.